I've noticed a couple times when my truck is cold (4.7 w87k mi) I get a little valve train noise, like a loose rocker. It doesn't sound like an old type writer or anything, just like one valve is loose. Does anyone else have this happen?

Do you know that our engines do not have hydraulic lifters? There is a valve clearance spec on an underhood sticker. Doing a tappet adjustment on a four-cam, 32 valve engine is not simple or cheap, so you might want to live with it.

The other possibility is an exhaust manifold gasket leak. Many times that will sound just like a valve tick. As the engine warms up the parts expand and the leak goes away. Just something else to check.

Do you know that our engines do not have hydraulic lifters? There is a valve clearance spec on an underhood sticker. Doing a tappet adjustment on a four-cam, 32 valve engine is not simple or cheap, so you might want to live with it.

The other possibility is an exhaust manifold gasket leak. Many times that will sound just like a valve tick. As the engine warms up the parts expand and the leak goes away. Just something else to check.

Put 8 oz of MARVEL MYSTERY OIL in the crankcase, 10 oz of LUCAS upper cylinder lube in the gas, burn-off half a tank and repeat. Change oil, change gas and air filters, add ~10 oz LUCAS to gas. Do the valve adjust if needed, or if you don't know for sure. Get someone to scope/analyze the engine for ignition problems (plugs/wires). If that doesn't fixit, trade-in on a new Tundra (jk)

Explain exactly what MMO and LUCAS is supposed to correct and how in this specific case. Sorry, but this sounds like an old-time shotgun approach rather than diagnosis of a problem and a specific repair.

Explain exactly what MMO and LUCAS is supposed to correct and how in this specific case. Sorry, but this sounds like an old-time shotgun approach rather than diagnosis of a problem and a specific repair.

Old time/shotgun... that's bad...how? I've used MMO for rough/clattering engines several times and it worked every time. When it works you've got a diagnosis AND a fix. If not, you've got bigger problems than the cost of snake oil. It's mostly solvents, detergents, and high film-strength oil that are relatively stable - enough to turn new oil black/nasty in minutes. They used it in the long-distance bombers of WWII to keep the engines running right with overdue servicing and bad fuel. I started using Lucas upper cylinder lube in the 04Titan and got better mileage, quiet valves, and better throttle response. The Tundra likes it too. (4-6 oz each fillup). Check the motorcycle forums. They're full of snake oil, but the favorites are MMO and Seafoam. I've used Seafoam in mowers that were carbon-fouled with excellent results. It REMOVES varnish/gum/sludge so effectively that I wouldn't use it in an engine I couldn't replace or rebuild. Maybe some of the race-people can add to this.

We could go on and on about this...my final word is buy it, use it, and make your own evaluation. Consumer Reports isn't always right...they didn't like Tundras, either. addendum:just last week my neighbor was pissed about bad gas (from a Chevron station)..the 90-something Buick Roadmaster was smoking, stumbling, idling rough. I put ~10 oz MMO in my gallon of chainsaw gas and dumped it in. 1 trip around the block (8 mi) and the old girl runs nice...nuff sed. bye

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